EP2804054B1 - Anti-adhesion device of a spiral on a bridge - Google Patents

Description

Field of the invention

The invention relates to an anti-adhesion device of a balance spring on a bridge and more particularly a balance spring belonging to a balance resonator - balance spring.

Background of the invention

Insulating materials, such as silicon and its compounds, quartz, diamond, glass, ceramic or others are increasingly used to produce parts of watchmaking micromechanics. As visible to figures 2 and 3 , it has been observed, in particular on a hairspring 7, in particular after an impact, the turns tend to stick to the bridge 2, which is detrimental to the isochronism of the oscillator.

This phenomenon can be aggravated by the contamination of the bridge 2 and / or the hairspring 7 by impurities or lubricant during manufacture or when worn, in particular during impacts. It is then understood that the turns of the hairspring 7 may adhere to the bridge because of the impurities or the lubricant, even if the hairspring is electrically conductive.

This phenomenon is known from the document EP1837721 . In particular, this document describes a watch movement in which the sprung balance resonator is mounted between a plate and a bridge. The insulating nature of the silicon, from which the hairspring is made, allows the formation of electrostatic charges on its surfaces. In some cases, the electrostatic attraction causes the surfaces of the balance spring and bridge to stick together (see figure 2 ). To avoid this effect, the hairspring is coated with a very thin layer (50nm or less) of a conductive material.

Summary of the invention

The aim of the present invention is to alleviate all or part of the drawbacks mentioned above by providing an anti-sticking device for a balance spring on a bridge.

To this end, the invention relates to a horological movement as defined in independent claim 1. Preferred embodiments are defined in the dependent claims.

By their manufacturing process, the balance springs obtained by etching a silicon or quartz wafer have particularly smooth faces conducive to adhesions. It is therefore understood, advantageously according to the invention, that, thanks to the anti-adhesion device, the faces of the balance-spring and of the bridge which are facing each other offer a potential adhesion surface which is much more limited, which makes it possible to limit these phenomena.

In addition, the invention relates to a timepiece characterized in that it comprises a horological movement according to one of the preceding variants.

Brief description of the drawings

• la figure 1 est une vue éclatée d'un mouvement horloger selon l'invention ;
• les figures 2 et 3 sont des vues respectivement au repos et en mouvement d'un spiral formé en matériau isolant se déplaçant en vis-à-vis d'un pont ;
• les figures 4 à 6 sont des vues schématiques de modes de réalisation de dispositifs anti-adhésion selon l'invention.

Other features and advantages will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the accompanying drawings, in which:

• the figure 1 is an exploded view of a watch movement according to the invention;
• the figures 2 and 3 are views respectively at rest and in motion of a hairspring formed from an insulating material moving vis-à-vis a bridge;
• the figures 4 to 6 are schematic views of embodiments of anti-adhesion devices according to the invention.

Detailed description of the preferred embodiments

To the figure 1 , one can see a partial representation of a watch movement 1 according to the invention intended to be mounted in a timepiece. The movement 1 preferably comprises a resonator 3 comprising a balance 5 and a hairspring 7 intended to regulate the movement 1. The resonator 3 is, preferably, mounted to pivot between a bridge 2 and another part 4 such as a bridge or a plate. To do this, the hairspring 7 comprises in particular a ferrule 10 whether or not integrally.

To the figure 1 , it can also be seen that the movement 1 preferably comprises an escape system 9 comprising an anchor 11 of the Swiss type and an escape wheel 13 intended to distribute the movements of the resonator but also to maintain it. The exhaust system 9 is preferably mounted between two bridges 6, 8 and a plate 4.

Advantageously according to the invention, the hairspring 7 and, optionally, its ferrule 10, can be formed from any material and in particular from silicon and its compounds, quartz, diamond, glass, ceramic, metal or metal alloy. The bridge 2 can also be formed from any material and in particular from a metal or a metal alloy.

In addition, the movement 1, preferably according to the invention, further comprises an anti-adhesion device 19, 19 ', 19 "of the hairspring 7, 7', 7" against the bridge 2, 2 ', 2 "comprising means 23, 23 ', 25, 25' of surface reduction between the faces of the hairspring 7, 7 ', 7 "and of the bridge 2, 2', 2" which are opposite to avoid variations in the rate of the movement 1.

As explained from figures 4 to 6 , advantageously according to the invention, the surface reduction means 23, 23 ', 25, 25' can be formed on the hairspring 7, 7 ', 7 "and / or on the bridge 2, 2', 2". By way of non-limiting examples, three embodiments of anti-adhesion devices 19, 19 ', 19 "exhibit, in figures 4 to 6 , four alternatives as surface reduction means 23, 23 ', 25, 25' according to the invention.

According to a first embodiment illustrated in figure 4 , the watch movement comprises a first example of an anti-adhesion device 19. The anti-adhesion device 19 comprises surface reduction means 23 formed on the bridge 2 ′. The surface reduction means 23 in the example of figure 4 comprise at least one recess 16 relative to the face 18 of the bridge 2 '. According to the invention, each recess 16 can form one or more series of grooves. In the example of figure 4 , a single spiral-shaped groove is formed on the face 18 of the bridge 2 '. However, in the case where at least two series of grooves are formed, they may or may not intersect. By way of example, the grooves can thus form sunrays or a knurling.

According to a second embodiment illustrated in figure 5 , the watch movement comprises a second example of an anti-adhesion device 19 '. The anti-adhesion device 19 'comprises first surface reduction means 23' formed on the bridge 2 "and second surface reduction means 25 formed on the hairspring 7 '.

The surface reduction means 23 'in the example of figure 5 comprise at least one protuberance 18 'relative to the face 16' of the bridge 2 ". According to the invention, each protuberance 18 'can form one or more series of ribs. In the example of figure 5 , a single spiral-shaped rib is formed on the face 16 'of the bridge 2 ". However, in the case where at least two series of ribs are formed, they may or may not intersect. For example, the ribs can thus form sunrays or knurling.

The surface reduction means 25 in the example of figure 5 comprise at least one recess 15 relative to the face 17 of the hairspring 7 '. According to the invention, each recess 15 can form one or more series of grooves. In the example of figure 5 , multiple parallelepiped-shaped grooves are formed on the face 17 of the hairspring 7 '. However, a single groove can run over all or part of the face of the hairspring or at least two series of grooves formed can intersect. By way of example, a single groove can be at a certain depth of the height over only a part of the thickness in order to form a groove on the face of the hairspring 7 'or series of grooves can form a knurling.

According to a third embodiment illustrated in figure 6 , the watch movement comprises a third example of an anti-adhesion device 19 ". The anti-adhesion device 19" comprises first surface reduction means 23 formed on the bridge 2 'and second surface reduction means 25' formed on the 7 "hairspring.

The surface reduction means 23 in the example of figure 4 comprise at least one recess 16 relative to the face 18 of the bridge 2 '. According to the invention, each recess 16 can form one or more series of grooves. In the example of figure 4 , a single spiral-shaped groove is formed on the face 18 of the bridge 2 '. However, in the case where at least two series of grooves are formed, they may intersect or no. By way of example, the grooves can thus form sunrays or a knurling.

The surface reduction means 25 'in the example of figure 6 comprise at least one protuberance 17 'relative to the face 15' of the hairspring 7 ". According to the invention, each protuberance 17 'can form one or more series of ribs. In the example of figure 6 , multiple parallelepiped-shaped grooves are formed on the face 15 'of the hairspring 7 ". However, a single rib may run on all or part of the face of the hairspring 7" or at least two series of ribs formed may intersect. For example, a single rib may be at a certain elevation from height over only part of the thickness in order to form a double shoulder on the face of the hairspring 7 "or series of ribs may form a knurling. .

Of course, the present invention is not limited to the example illustrated but is susceptible of various variants and modifications which will appear to those skilled in the art. In particular, it is understood that the anti-adhesion devices can take other forms, in particular geometric. In addition, the embodiments and / or the alternatives can be combined with one another depending on the configurations of the movement used. It will be understood in particular that either the bridge or the balance spring or both are modified in order to reduce their potential contact surface.

Claims (9)

1. Timepiece movement (1) including a resonator (3) formed by the cooperation of a balance (5) with a balance spring (7, 7', 7"), said resonator being pivotally mounted between a bar (2, 2', 2") and another part (4), characterized in that the timepiece movement (1) further includes a device (19, 19', 19") for preventing adhesion of said balance spring against said bar comprising at least one recess and/or protruding portion, defining surface decreasing means (23, 23', 25, 25') formed on the bar (2', 2") and allowing the contact surface to be limited when the faces (15', 16', 17, 18) of said balance spring and of said bar touch each other.
2. Timepiece movement (1) according to the preceding claim, characterized in that the surface decreasing means (25, 25') is also formed on the balance spring (7', 7").
3. Timepiece movement (1) according to claim 1 or 2, characterized in that the surface decreasing means (23, 25) includes at least one recess (15, 16) in relation to the faces of said balance spring and of said bar which face each other.
4. Timepiece movement (1) according to the preceding claim, characterized in that said at least one recess (15, 16) forms series of grooves.
5. Timepiece movement (1) according to the preceding claim, characterized in that at least two of said series of grooves are secant.
6. Timepiece movement (1) according to claim 1 or 2, characterized in that the surface decreasing means (23', 25') includes at least one protruding portion (17', 18') in relation to the faces of said balance spring and of said bar which face each other.
7. Timepiece movement (1) according to the preceding claim, characterized in that said at least one protruding portion (17', 18') forms series of ribs.
8. Timepiece movement (1) according to the preceding claim, characterized in that at least two of said series of ribs are secant.
9. Timepiece characterized in that the timepiece includes a timepiece movement (1) according to any of the preceding claims.

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